There are a number of autostarted akonadi agents that I do not use (migration agent, email alert,…). I know that I can disable them by removing 'Autostart' in the line X-Akonadi-Capabilities=Unique,Autostart in these files. However, this does not seem like the proper way to do it. (Will be lost upon updates.) There does not seem to be a way to override this properly. Please implement one. Ideally this is based on being able to choose which resources to Autostart (taking into account required dependencies), but if necessary by putting a modified version of the files in a location that has higher precedence.
It should already work if you put the modified .desktop file to a custom path that is specified in XDG_DATA_DIRS env variable before the default one (/usr/share). Then the modified file should take precedence. We are not going to implement any user configuration for this - users don't know what is really needed for the whole system to work, so they would disable things like the migration agent and then complain to us that Akonadi doesn't work... The grand plan is to implement start-and-shutdown-on-demand capability for Akonadi and its resources so that the processes are not running when they are not needed. We are missing one important bit in Akonadi before implementing this feature though, so keeping this open for now.
does turning off the plugins from the KMail configuration dialog help?
(In reply to Allen Winter from comment #2) > does turning off the plugins from the KMail configuration dialog help? No, those plugins were turned off anyway in my setup. After removing the archiving agent and the send-later agent were re-added, but remained off-line. The mail notification agent was re-added and went on-line.
(In reply to Daniel Vrátil from comment #1) > […] the migration agent […] What is it for, actually? (I experienced no visible adverse effects after disabling it…)
When you disable the agents in KMail configuration they will still run, but they will be completely inactive, using almost no memory and no CPU, just quietly sitting there. The migration agent can performs payload and metadata migration which require understanding the meaning of the payload, since Akonadi only sees the payload as a binary blob.